There isn’t really a freedom to medical advice in the same way that there is freedom to attend an AntiVax moron give a speech, or hold any other type of idiotic belief. This is one reason why doctors have to be held accountable for their diagnosis, and pay millions for malpractice insurance. Conversion therapy can continue to exist, it just can’t call itself a viable medical option. So Michelle Bachmann’s husband can continue to talk to young boys about their desire to get it in the butt, but his “clinic” can no longer claim to actually be dispensing any sort of medical diagnosis. I’d say it’s more similar to the AntiVax doctor who had his medical license taken away when he forged research to show a link between autism and Vaccines as opposed to some sort of free speech issue. In this (ex)doctors case he continued to speak freely about his belief that the MMR vaccine causes autism, he just has to write books about it instead of working within a medical profession.
I’d say that this is a good thing. I imagine in the years to come, as more of the human genome is mapped and understood, that the obvious will soon be proven by science, and SURPRISE we’ll find out that certain people are born as gay or straight and it wasn’t because satan infested their body with demonic possession. In 30 years people like Bachmann’s husband will look like complete lunatics.